Estimating earth surface properties

Question 1

What is a vegetation index?

Answer 1

They highlight the prevalence of vegetation but remove the remove the ‘noise’ other information that alters the usefulness of the data such as cloud over

Question 2

What does NDVI stand for?

Answer 2

Normalised Difference Vegetation Index

Question 3

What is the soil line?

Answer 3

The linear relationship between the NIR and red reflectance of bare soil characterised by slope and interception

Question 4

What does the magnitude of reflectance depend on?

Answer 4

Vegetation

Question 5

What does low density vegetation look like (on a plot)?

Answer 5

High reflectance (in red wavelength) because you can see more soil

Question 6

What does a lower NDVI value signify?

Answer 6

Vegetation is less healthy and dying due to a lower chlorophyll content, and/or sparse vegetation

Question 7

What does a high NDVI value signify?

Answer 7

Healthy dense vegetation

Question 8

What happens as vegetation matures?

Answer 8

As vegetation matures during growing season, high NIR and lower red values of reflectance, healthier and more dense vegetation = higher NDVI

Question 9

What does LAI stand for?

Answer 9

Leaf area index

Question 10

What are the disadvantages of NDVI?

Answer 10

Reduced sensitivity at high biomass or over dense vegetation
Factors that influence the red and NIR reflectance such as soil wetness will influence NDVI
Sensitive to background variation e.g. soil brightness

Question 11

What does SAVI stand for?

Answer 11

Soil adjusted vegetation index